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YOUR RESEARCHDrivetrain boominess - what would you do?
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Replace clutch
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Leading evidence: 'Replace clutch' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace clutch' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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911uk: 1 discussions
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Thankfully, the Mark 2 gearbox mount fixed the problem and I stopped thinking about this as an issue.
Some thoughts, please Gents (and girls!).
When I installed the Powerflex gearbox mount (Mark 1), there was a horrible vibration/boominess from the back end around 3-4000 RPM. I remember a lot of guys not having this problem and one of you guys asking if I had had a new clutch, which I have had. Thankfully, the Mark 2 gearbox mount fixed the problem and I stopped thinking about this as an issue.
Having recently installed the 993/964 RS engine mounts, the boom is back and it has got me thinking: do I have a drivetrain balance issue that needs addressing? I'm concerned that this vibration cannot be good for all manner of mechanical parts.
What would you guys do:
a. Just fit normal engine mounts and ignore the issue?
b. Change the clutch
c. Get a drivetrain balance done - thoughts on where and how appreciated
d. Something else (with details, please)?
Option a.
B - won't affect it I'd have thought ?
C - Again doubtful, and the gearbox would have to come out to get at flywheel, which in any case if dual mass can't be balanced. Or difficult in any case.
D - if you moved the engine a bit to remove and fit new mounts, maybe something else is touching or rubbing where it shouldn't and causing a harshness at a resonant frequency?
I would try a new OE gearbox mount and keep the RS engine mounts, on the basis they make more difference to the drive feel. Hopefully the vibration is a resonance arising from the combination of the two.
I have started to get a chatter from the gearbox at idle with clutch disengaged since fitting the rs engine mounts and gearbox insert. The rubber previously soaked that up, I guess I might remove the insert and see how that is as didn't feel much difference from the insert anyway
Update on this: I removed the gearbox mount inserts and things are much, much better. Also found a slightly loose exhaust mount and tightened it up, as well.
Not sure which one actually cured the problem, but the engine mounts weren't the cause, anyway. :thumb:
